1. Field of Invention
The present invention relates generally to heat exchange systems, and more particularly to heat exchange systems that use at least two tubes, one concentrically positioned within the other and arranged in a serpentine manner.
2. Description of Prior Art
Heat exchange systems are sometimes used in the liquid food processing industry for destroying bacteria that may be present in the food product. Examples of what are generically referred to as xe2x80x9cliquid food productxe2x80x9d that is subjected to a heat exchange system for destroying harmful bacteria include milk, liquid egg product, juices, slurries, slurries in suspension, pharmaceuticals, and other beverages. In use, the food product flows through an inner tube in a first direction, while the heating/cooling media flows through the outer tube in the opposite direction. Such a system is generally referred to as a tube-in-tube arrangement, or a two-tube arrangement, but the same concept has been applied to three tube arrangements, wherein heating/cooling media flows in an inner-most tube and the outer-most tube in one direction, while food product flows through the central tube in the opposite direction.
It is useful for these types of heat exchange systems to be arranged in a serpentine (or back and forth) manner to conserve space, and with a slight downward pitch to facilitate fluid drainage when necessary. To achieve this arrangement, a U-shaped tube generally interconnects two product tubes extending in spaced parallel relation to one another. The heating/cooling media tubes are also interconnected to one another through connecting tubes, but not necessarily U-shaped tubes. In order to clean these systems without having to dismantle the tubes, the tubes are generally sloped downwardly in order to permit gravity to assist in draining them.
For obvious reasons, it is necessary to clean and decontaminate the tubes on a regular basis. To clean the tubes, they must first be drained and then flushed with a cleaning solution. Connecting a pump to a terminal tube to force the food product through the tubes, and then pumping cleaning fluid through the system generally accomplish this cleaning process. To prevent the fluid from backing up in the tubes due to pressure differentials created at the bends, the U-shaped tubes are generally of a greater cross-sectional diameter than are the product tubes. Tapering flow reducers are used to interconnect the U-shaped tubes to the product tubes. The prior art flow reducers used at the junctions of the U-shaped connecting tubes and the food product tubes generally uniformly taper from the diameter of the U-shaped tube to the diameter of the food product tubes. In other words, the flow reducers are concentric in cross-section.
The concentric flow reducers improve over those systems not utilizing flow reducers at the bends (i.e., where the U-shaped tubes are of the same cross-sectional diameter as the product tubes). However, in systems employing concentric flow reducers, liquid product tends to gather and become entrapped along the bottom of the reducer that effects the ultimate change in direction of the flow. Such entrapped product may result in admixture with the cleaning fluid when it passes through the tubes, thereby resulting in contamination of the cleaning fluid and dilution of that portion of the product. Thus, a need exists for an improved flow reducer that prevents liquid product from becoming entrapped in the flow reducers.
3. Objects and Advantages
It is therefore a principal object and advantage of the present invention to provide a flow reducer for use in a heat exchange system that is effective at preventing liquid product from becoming entrapped in the flow reducers.
It is another object and advantage of the present invention to provide a flow reducer in a heat exchange system that may be efficiently interconnected or disconnected from the system.
Other objects and advantages of the present invention will in part be obvious, and in part appear hereinafter.
In accordance with the foregoing objects and advantages, the present invention provides a U-shaped connecting tube utilizing flow reducers for use in heat exchange systems of the type having a plurality of product tubes of a first cross-sectional diameter and in which liquid product flows and at least one media tube of a second cross-sectional diameter different from the first cross-sectional diameter, concentrically positioned around the product tube and in which heating or cooling media flows. The U-shaped tube generally includes a U-shaped portion of substantially constant third cross-sectional diameter greater than the first cross-sectional diameter; a first flow reducer extending from the U-shaped body portion to a first of the product tubes, and tapering from the third cross-sectional diameter to the first cross-sectional diameter; a second flow reducer of eccentric (i.e., non-uniform taper) cross-section, extending from the U-shaped body portion to a second of the product tubes, and tapering from the third cross-sectional diameter to the first cross-sectional diameter. The eccentric cross-sectional shape of at least one of the two flow reducers prevents product from gathering and becoming entrapped at the bottom of the reducer.